Matt Nagy doesn't want you to get too excited about David Montgomery.

The Chicago Bears rookie running back packed a lot of highlight-stick moments into just three carries, three catches and one touchdown in an otherwise dreary preseason game against the Carolina Panthers last week. Head fakes. Spin moves. Stop-and-go cuts. Soft hands on sideline tosses.

After the game, even the Bears head coach sounded swept up in the excitement.

"He runs hard. He runs really, really hard," Nagy said in his postgame press conference. "He runs violent. He's angry when he runs, and he's tough to bring down with that first defender, so we like that. And you could see what he can do in the pass game as well, made some nice catches and run after the catch."

But Nagy cooled down a bit the next day.

"You guys were blowing it up like it was some great run," he told reporters, smiling as he did so, per Dan Wiederer of the Chicago Tribune. "It was just average. It was good. I mean, jeez."

Jeez, where would anyone get the impression that Montgomery looked like a hard, angry, violent runner from, Coach?

"I pumped him up a little bit the other night," Nagy added. "Now I've got to pump the brakes on him a little bit."

Nagy isn't a big believer in the preseason. He barely played his starters last year, and he's unlikely to play them much this year. (Quarterback Mitchell Trubisky started the opener, handed off three times, then exited.) That leaves us with little to talk about except Montgomery and the reports out of Bears camp. And those reports haven't been all that encouraging.

• Trubisky has gotten, to be polite, very mixed reviews in practice. Bears fans are hoping the third-year quarterback is poised to leap into Jared Goff-Carson Wentz territory. Folks who grind tape and stats are bracing for him to retreat into Blake Bortles territory.
• Chicago's Bachelorette-like kicking competition has settled into a duel between Eddy Pineiro and Elliott Fry. The Bears' kicking situation isn't as desperate as, say, the Jets and Vikings' situations right now. But there's still a risk of double-doink disasters at the worst possible moments.
• The defense once again looks nasty. But it probably won't generate 36 takeaways like it did last season, because even historically great defenses cannot sustain that turnover level.

It all paints a worrisome picture of a team whose quarterback might backslide and whose defense should slip a teensy bit due to the gravitational pull of regression to the mean. That would be enough to turn last year's division winner into just another Wild Card wannabe, or worse.

That's where Montgomery steps in. 

The Bears drafted Montgomery out of Iowa State in the third round this past spring. He rushed for more than 1,000 yards for the Cyclones in both 2017 and 2018, adding some receiving production and 24 total touchdowns over two seasons. He left college with a reputation as a no-nonsense tackle-breaker with outstanding balance and good vision, plus solid marks as a receiver and pass protector.

Montgomery lasted until the third round because he ran a 4.63-second 40 at the combine, and also because quality running backs often last until the third round these days. You know all the talking points: running backs don't matter, committee backfields and so forth. If a college rusher doesn't blow up the Saturday highlights and combine workouts like Saquon Barkley, he's just another guy in the draft pool.

The Bears drafted Montgomery to replace Jordan Howard, a former 1,000-yard back who was traded to Philly to replace Jay Ajayi, a former 1,000-yard back who…you get the idea. Running backs are highly interchangeable. Montgomery is slated to split time with Tarik Cohen, the human joystick who can turn every screen pass into a Mario Party, and if he replicates Howard's 1,000ish yards and six to nine touchdowns, it will matter more to your fantasy standings than to the NFC North standings. 

Or will it?

Trubisky was a pretty convincing Patrick Mahomes cosplayer in the first half of the season, completing 70.0 percent of his passes and throwing eight touchdowns in his first four games while propped up behind the wheel of Nagy's Chiefs-lite offense. But Trubisky's stats and effectiveness waned as the season wore on and opponents caught on to what he likes to do: He threw for less than 200 yards in four of his final seven starts. 

Granted, the Bears defense kept a cleat on the necks of most opponents last season, so Trubisky didn't have to throw for hundreds of yards to win games. But he was neither consistent nor efficient. His best plays came when Nagy drew up extra-fiendish whiteboard wizardry or when someone like Cohen turned a short toss—often after Trubisky broke the pocket—into a huge gain.

In other words, Trubisky needs to be surrounded by playmakers in an unpredictable scheme to be effective. The same can be said of just about any quarterback, of course. That's the point. If the pessimistic chatter out of camp is true, their quarterback will be ordinary at best, and the Bears will need other advantages on offense, especially if the defense can no longer spot them two turnovers per game.

Fortunately, Montgomery offers advantages that Howard did not provide last year.

Howard averaged just 3.7 yards per rush last season and caught just 20 passes. He was a grinder with limited versatility and big-play juice. The Bears offense thrived on misdirection and adaptability, but they became run-heavy and conventional with Howard on the field. Opponents exploited that tendency, which made it harder for Nagy to scheme up easy reads and throws for Trubisky.

Montgomery is more like Cohen as an all-purpose playmaker, but he has the size and durability to handle Howard's cloud-of-dust tasks. Opponents won't know what's coming when Montgomery is on the field, and his electrifying open-field moves should turn a few of Howard's old four-yard runs and swing passes into big plays.

Montgomery could make the Bears offense more efficient and explosive. That would take pressure off Trubisky and the defense. And, yes, the kickers, too.

Perhaps Nagy was right to pump the brakes after a handful of highlights. But the Bears may have stolen a superstar in the third round. And Montgomery may be just what they need to create a very Bears-like rushing-and-defense, quarterback-foolproof Super Bowl team.

No wonder Nagy is excited. Even if he's trying to hide it.

Mike Tanier covers the NFL for Bleacher Report. Follow him on Twitter:@MikeTanier.